The Census Bureau publishes data for 1-year, 3-year, and 5-year estimates, with population thresholds set for the 1-year and 3-year estimates to produce reliable data. Here is a brief comparison of the three types of estimates:

1-Year Estimates

3-Year Estimates

5-Year Estimates

Published for selected geographic areas with populations of 65,000 or greater

Published for selected geographic areas with populations of 20,000 or greater

No population thresholdand published for small geographic areas

Represent the average characteristics over a calendar year

Represent the average characteristics over the 3-year period of time

Represent the average characteristics over the 5-year period of time

Have fewer published geographic areas than the 3-year and 5-year estimates

Have fewer published geographic areas than the 1-year estimates but less than the 5-year estimates

For data quality and geographic reasons, some tables are published with specific geography restrictions. For example, the able B05001-PR, Citizenship Status in Puerto Rico, is produced for Puerto Rico only, and the table B08501, Means Of Transportation To Work By Age For Workplace Geography, is only produced for the work place geographies. Appendix E has a complete list of tables and their geography restrictions, and Appendix F has a complete list of the published summary levels and components for this release. Other examples include the quality measures tables (the B98 series) and detailed occupation tables.

Some data values represent unique situations where either the information to be conveyed is an explanation for the absence of data, represented by a symbol in the data display, such as "(X)", or the information to be conveyed is an open-ended distribution, such as 115 or greater, represented by 115+.

The following special data values can appear in the ACS Summary File table as an explanation for the absence of data:

Missing Value = ""

A missing string indicates that the estimate is unavailable. (This appears in the estimates and margins or error files as two commas adjacent to each other without anything between them, or if the last cell in a data file is filtered then you get a comma followed immediately by a carriage return or EOF.) A missing value indicates when an estimate is missing because of filtering for geographic restrictions, coefficients of variations (CV), or was removed due to the Disclosure Review Board's (DRB) requirements. For more detail on filtering, please see Appendix C.5.

Dot = "."

A dot indicates when the estimate has no sample observations or too few sample observations. In the margin of error files, this value could also indicate that the margin of error is unavailable for a median estimate that has been replaced with a jam value.

Zero = "0"

A "0" entry in the margin of error column indicates that the estimate is controlled. A statistical test for sampling variability is not appropriate. This is similar to the "*****" symbol used in American FactFinder.

Negative 1 = "-1"

This indicates that an estimate does not contain a Margin of Error. Tables B00001, B00002, and tables starting with B98 and B99 do not have margin of error (MOE) associated with them. The MOE calculations are set to -1 for these tables.

Jam Values for Medians

The following is a listing of the "jam values" for medians. Jam values are numeric placeholders that represent open intervals above or below a number. For example, the jam value of "2499" for table B10010 does not indicate a dollar amount, but rather it means that the median is below $2,500 and is not available.

Jam Value

Actual Meaning

Use for Medians

0

1 or less

Age, Duration of Marriage

9

9.0 or more

Rooms

10

10.0 or less

Gross Rent as Percentage of Income, Owner Costs as Percentage of Income

50

50.0 or more

Gross Rent as Percentage of Income, Owner Costs as Percentage of Income

B00001, B00002, B98001, and B98002 are sample counts, not estimates, and do not have margin of error (MOE) associated with them. Tables in series B99* imputation tables and B98* (except B98001 and B98002) quality measure tables do not provide margin of error calculations. The margin of error calculations are set to -1 for these tables.

There are a few special rules on how certain margin of error are determined for ACS estimates. The accuracy of the estimate (decimal place) within the detailed tables determines how many digits the margin of error is rounded.

The only exceptions to these rules are tables B19082 (Shares of aggregate household income by quintile) and B19083 (index of income inequality, commonly known as GINI). B19082 has estimates rounded to one decimal place and MOE rounded to two decimal places. B19083 has estimates rounded to three decimal places and MOE rounded to four decimal places.

Filtering rules, based on statistical reliability of the survey estimates, are used because certain geographic areas contain detailed tables include estimates whose level of reliability is unacceptable. The data release rules for the American Community Survey data tables include the following.

Every base table consists of a series of estimates. If more than half the estimates are not statistically different from 0 (at a 90 percent confidence level), then the table fails. Each estimate is subject to sampling variability that is summarized by its standard error. Dividing the standard error by the estimate yields the coefficient of variation (CV) for each of the estimates. (If the estimate is 0, a CV of 100 percent is assigned.) To implement this requirement for each table at a given geographic area, CVs are calculated for each of the table's estimates, and the median CV value is determined. If the median CV value for the table is less than or equal to 61 percent, the table passes for that geographic area; if it is greater than 61 percent, the table fails. Tables that are too sparse will fail this test. In that case, the table will not be published for that geographic area. Whenever a table fails, a simpler table that collapses some of the detailed lines together can be substituted for the original, more detailed table. The rules are then applied to the simpler table. If it passes, the simpler table is released. If it fails, none of the estimates for that particular table is released for this geographic area. These rules are applied to single-year period estimates and multi-year period estimates based on three years of sample data.

The estimates in the summary files are stored using standard notation instead of in scientific notation. The estimates are stored as whole numbers. The largest estimate in a Summary File contains 14 digits.

C.7. Sequences Used Only for United States Tables or Only for Puerto Rico Tables

There are several tables that differ between the United States (the 50 states and the District of Columbia) and Puerto Rico. The tables are different because the comparable tables may they contain different metadata (such as C06001 having 45 cells and C06001PR having 37 cells). To identify what tables are available for Puerto Rico only look for the "PR" suffix in the table id (e.g. C06001PR). Because of that, there are sequence files that apply only to the 50 states and the District of Columbia or only to Puerto Rico:

US/State-only Sequences - Missing PR Data

PR Only Sequences - Missing US/State Data

1 (US)

109 (PR)

2 (US)

110 (PR)

17 (US)

111 (PR)

18 (US)

112 (PR)

20 (US)

113 (PR)

21 (US)

114 (PR)

22 (US)

115 (PR)

23 (US)

116 (PR)

24 (US)

117 (PR)

107 (US)

118 (PR)

Therefore, for sequences 109-118 for areas other than Puerto Rico, the sequence files exist, but they are blank.

There are six tables with more than the maximum 245 cells that cannot fit into a single sequence, so each of these tables is broken into multiple sequence files. The table below shows the tables that contain multiple sequences:

Tables That Are Contained in More Than One Sequence File

Table ID

Table Title

Sequences

B24121

Detailed Occupation By Median Earnings In The Past 12 Months For The Full-Time, Year-Round Civilian Employed Population 16 Years And Over

77, 78, 79

B24122

Detailed Occupation By Median Earnings In The Past 12 Months For The Full-Time, Year-Round Civilian Employed Male Population 16 Years And Over

80, 81, 82

B24123

Detailed Occupation For The Ful-Time, Year Round Civilian Employed Population 16 Years And Over

83, 84, 85

B24124

Detailed Occupation For The Full-Time, Year Round Civilian Employed Male Population 16 Years And Over

86, 87, 88

B24125

Detailed Occupation For The Full-Time, Year Round Civilian Employed Male Population 16 Years And Over

89, 90, 91

B24126

Detailed Occupation For The Full-Time, Year Round Civilian Employed Female Population 16 Years And Over

92, 93, 94

The tables on the list are only produced at the United States national level (summary level 010), and the files for these sequences will be blank for all other summary levels.